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(10) High Blood Pressure

 Non-pharmacological treatment

Changing your lifestyle, including diet, exercise and smoking, will help to lessen the risk of heart attacks and strokes.

Can I bring my BP down to normal without taking drugs?

The answer depends on how high your average BP is. Generally speaking, if after several measurements over a period of 4-6 weeks, your BP remains raised (averages more than 150/90 mmHg) and your risk of heart attack or stroke is high when estimated from a cardiovascular risk chart, you will need to consider options to reduce both your BP and overall cardiovascular risk.

As mentioned BP alone is only one of several risk factors that determine your likelihood of suffering a heart attack or stroke. It makes sense to address your overall cardiovascular risk by changing all your risk factors. Cholesterol levels

The following questions explain all about cholesterol.

I am going to have a cholesterol test soon. What is cholesterol and why is it important?

Cholesterol is an essential component of all body cells and of many important circulating chemicals in the blood (hormones). It is formed from many different sorts of fats and oils in what you eat, including cholesterol itself, which is present in large quantities in some foods such as egg yolks, liver, kidneys, meats and fish roes. It is then distributed where it is needed in the body. If there is a surplus, most of this is stored in the liver, but some remains circulating in the blood. Blood cholesterol concentration is now measured in millimoles per litre (normally written as mmol/litre), except in North America, which still uses milligrams per deciliter (normally written as mg/dl). This value varies between countries (mainly because of differences in fat intake), from an average below 4 mmol in China, to nearly 6 mmol in the UK. For individuals, otherwise normal people may have blood cholesterols varying from about 3.5 mmol to about 15 mmol.

The reason the concentration of blood cholesterol matters is that the higher it is, the more it is deposited as waxy plaques on the walls of coronary arteries supplying blood to the heart, to brain arteries, and to the aorta and leg arteries, which then causes narrowing of the walls. The narrowing tends to cause clotting and thus partial or complete destruction of the organs supplied by these arteries.

Scientific studies in many countries over many years have confirmed a close connection between average levels of blood cholesterol and coronary heart disease in people aged under 65 in whole populations, and a somewhat less close connection for individuals. There is no doubt whatever that, in all societies where average blood cholesterol is low, coronary heart disease is rare, or that, in all societies where it is high, coronary heart disease is common. This remains true even if other risk factors for coronary heart disease are common in low-cholesterol societies, or low in high-cholesterol societies. For example, although high BP and heavy smoking are extremely common in China, resulting in many strokes, coronary heart disease remains rare; whereas in western countries where both smoking and uncontrolled high BP have become much less common, but average blood cholesterol has not fallen, as in Sweden, coronary heart disease remains common.

The media talks about good and bad kinds of blood cholesterol? What are these?

When doctors talk loosely about ‘blood cholesterol’ they normally mean total cholesterol, but this is actually made up of three parts. If you leave about 10 ml of blood standing in a glass tube until it has clotted, the cholesterol it contains becomes easily visible as a cloudy yellowish substance, occupying the top quarter or so of the tube. It looks like what it is, a sort of fat. If you put this in a high speed centrifuge, the yellow stuff separates out according to molecular size and weight, into three parts:

• High density lipoprotein (HDL)

• Low density lipoprotein (LDL), and

• Very low density lipoprotein (VLDL) cholesterol.

LDL and VLDL cholesterol are ‘bad’ cholesterol, the source of waxy plaques on the walls of the aorta, coronary arteries, brain arteries and leg arteries that ultimately weaken or block these vessels, and cause organ damage by clotting or bleeding. HDL cholesterol, on the other hand, is ‘good’. Many studies have shown that concentrations of HDL cholesterol above about 1.5 mmol make coronary heart disease less likely and low levels (below 1 mmol) make it more likely. This is probably because HDL is the form in which cholesterol is transported in blood before storage in the liver or excretion in bile. LDL and VLDL are thus measures of a tendency to harmful deposition of cholesterol in artery walls, whereas HDL is a measure of beneficial storage of cholesterol in liver or excretion in bile.

As LDL and VLDL together usually account for about 80% of total blood cholesterol, total blood cholesterol can generally be accepted as a valid though approximate measure of ‘bad’ cholesterol, while ignoring the contribution from ‘good’ cholesterol. Most laboratories now report both HDL and total cholesterol and some of the risk charts estimate cardiovascular risk based on the HDL/total cholesterol ratio.

Sophisticated measurements of blood fats (lipids) often also include triglyceride, the form in which fat is first absorbed from the gut. Except in the special case of what is known as ‘Inherited familial hypercholesterolaemia’, measurement of triglyceride is rarely of practical value. High values are commonly associated with fatness, or high alcohol consumption, or both. Once these are taken into account, high triglyceride is not a good predictor of whether you will have a heart attack.

Measurements of cholesterol fractions and triglyceride are obviously more complex and costly for the laboratory, but it is also more bother for you because, while total cholesterol and HDL cholesterol can be measured accurately on any sample of Non-phamacological treatment blood, LDL, VDL, and triglyceride can be measured accurately only after a minimum fasting period of 12 hours, during which no food or drinks other than water, can be taken.

What are the benefits of treating my high cholesterol level as well as my high BP?

Raised cholesterol (‘dyslipidaemia’) is another risk factor for coronary heart disease. There is a two-fold increase in the risk of suffering a heart attack or stroke in people who have raised total and LDL cholesterol and low levels of HDL, compared to people without such findings. The relationship between high triglyceride levels and future risk of cardiovascular disease (particularly heart attack) is less clear cut. Reducing your cholesterol levels with drugs will be later, but the key is that your overall risk of heart attack or stroke is calculated, as drug treatment can be beneficial, but greater benefit is gained from treatment of people with high risk.

My father has high blood cholesterol. Is it likely that I will have high levels as well?

Yes, unfortunately very much so. Regardless of inheritance, people on an extremely low-fat diet, for example the poorest people in China, cannot have high blood cholesterol levels, but once people are rich enough to eat as much as they want of the cheaper foods available, the main determinant of individual blood cholesterol levels is not personal diet, but personal chemistry, and this is strongly inherited. Some people can eat a lot of fats and oils without getting either a high blood cholesterol or cholesterol plaques in their arteries; others are not so lucky, and the main difference lies in their genes.

A few people (about 1 per 500) have inherited genes for very high blood cholesterol from one parent (‘heterozygous hypercholesterolaemia’), and even fewer (less than 1 per 1000) have inherited them from both parents (‘homozygous hypercholesterolaemia’).

Homozygotes mostly die from coronary heart attacks before they reach 30. Heterozygotes have a peak risk of coronary heart attacks between the ages of 20 and 39 but, if they survive this, subsequently have about the same risk as the general population. All these people have blood total cholesterol levels around 9–15 mmol, with very high LDL and VLDL cholesterol levels, very low HDL cholesterol levels, and usually very high triglyceride levels. They all deserve specialist investigation and initial counselling and treatment at a special lipid clinic. As well as skilled dietary advice, they invariably need cholesterollowering medication. ‘Familial hypercholesterolaemia’ should be sought for in the surviving relatives (including children and grandchildren) whenever anyone has a fatal or non-fatal coronary heart attack under the age of 50.

The vast majority of people with ‘high blood cholesterol’ are not in this category; they simply eat what most of us eat, and suffer the consequences of any diet in which 40% or more of all energy is consumed as fat.

Can I do anything to increase ‘good’ HDL blood cholesterol?

Yes. HDL cholesterol is increased by exercise, by stopping smoking, and by drinking alcohol. The latter is possibly the main reason for low death rates from premature coronary heart disease in France, but correspondingly high death rates for cirrhosis of the liver more than make up for this!



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